This chart illustrates the staggering difference in housing affordability between London and the rest of the UK

Dan Kitwood / Getty LONDON — The gulf between London and the southeast's property market and the rest of the UK is staggering — particularly when it comes to affordability.

While housing across the country has become more than twice as unaffordable on average in the past two decades, the gap between so-called "prime" central London areas — where housing is most unaffordable — and the UK's most affordable areas has widened by an even bigger factor.

"In 2016, Kensington and Chelsea was the least affordable area to buy a property in England and Wales. It had the highest ratio of house prices to annual earnings, with house prices being 38.5 times the median gross annual earnings," the ONS' release said. "This has increased since 1997 when house prices were 11.8 times earnings."

By contrast, Copeland in the northwest county of Cumbria had the most affordable housing in 2016, although prices were still close to three times average earnings.

"Although Copeland is the most affordable local authority in England and Wales, it does not mean that this local authority has the lowest house prices or the highest earnings; rather it has the highest earnings in relation to the house prices," the ONS said.

The chart from the ONS below illustrates the issue of the stretching gap between the most and least affordable parts of the country. While prices in Copeland have increased a little in terms of affordability, Kensington properties have spiked upwards: Office for National Statistics